My Baby Of 3.5 Years Is Regularly Getting An Attack

My baby of 3.5 years is regularly getting an attack of severe cough with phlegm and fever every month. It is treated with Cheston / Ascoril expectorant, along with paracetamol syrup, usually Fepanil. It lasts for 4 to 5 days and then she gets better. The same repeats exactly every month. This has been going on for the last 6 momths. Our doctor has introduced Septilin syrup once daily since last month. Still it has recurred again today exactly one month after the last episode. Is it something dangerous? Should we go to a different doctor?